A fan used in a computer is mainly used to discharge the thermal energy released by the operation of a host computer to the outside. The conventional host computer is often placed in a corner because of its monotony. In order to increase the visibility of the host computer, there are many transparent or light-emitting cases available in the market that can render the host computer different light changes, a variety of cooling fans, heat-conducting water drains and the like which can emit different light changes are provided in the host computer so as to enhance the visibility of the host computer through different light changes.
For example, U.S. Pat. No. 9,777,918 discloses a light-emitting cooling fan structure dissipating heat, wherein a circuit board is arranged in a fan body, and the circuit board is sequentially provided with a first light-guiding frame and a second light-guiding frame, and the circuit board is provided with a plurality of side-light lighting elements. Every two side-light lighting elements are reversely arranged and spaced on a rim of the circuit board. A bottom of the first light-guiding frame is annually provided with a lighting reflection layer, and the plurality of side-light lighting elements is arranged below the lighting reflection layer. The lighting reflection layer reflects light sources of the side-light lighting elements to pass through an edge to a top of the first light-guiding frame and the second light-guiding frame, thereby uniformly scattering and forming a circular light source, such that the cooling fan structure presents a unique lighting effect of a uniform annular light source.
However, the aforementioned U.S. Pat. No. 9,777,918 can provide a uniform annular light source on one side of the cooling fan. However, this patent does not provide a uniform lighting effect for the entire cooling fan. Meanwhile, the one-side lighting will make the use of the cooling fan more monotonous.